1. Field of the Invention
The present invention relates to a semiconductor device having a ferroelectric capacitor, and to a method of manufacturing the semiconductor device.
2. Description of the Related Art
A semiconductor device storing data in a nonvolatile manner using a ferroelectric capacitor has been conventionally known (such a semiconductor device is also called a ferroelectric random access memory (FeRAM) below). Among FeRAMs, a chain FeRAM is configured of cell array blocks each formed by serially connecting multiple pairs of parallel-connected transistors and ferroelectric capacitors. The ferroelectric capacitor is formed, for example, by vertically stacking a lower electrode, a ferroelectric film, and an upper electrode on a semiconductor substrate covered with an insulating film.
When the electrodes and ferroelectric film are vertically stacked, the electrode on either side of the ferroelectric film extends horizontally. Such a horizontal ferroelectric capacitor has a problem that, when size reduction is to be achieved, a sufficiently large area cannot be secured for the capacitor, thereby reducing the amount of signal. To address this problem, a semiconductor device having a ferroelectric capacitor having electrodes vertically extending on both sides of a ferroelectric film has been disclosed. To obtain such a ferroelectric capacitor, for example, after formation of a capacitor electrode film, a groove-like opening part is formed by etch-removing the capacitor electrode film vertically to the film surface, and a ferroelectric film is embedded in that vertical opening part.
In the semiconductor device disclosed, the left and right electrodes are processed by dry etching (reactive dry etching (RIE)) in order to embed the ferroelectric film between the electrodes. As a result, the electrodes suffer heavy damage on interfaces with the ferroelectric film, leading to a problem of deterioration of the capacitor characteristics.